1. Field of the Invention
This invention relates generally to a method and apparatus for controlling an internal combustion engine, and more particulary to a microprocessor-based electronic engine control system having a memory preprogrammed with various control laws and control schedules responsive to one or more sensed engine-operating parameters for generating signals for controlling fuel injection, ignition timing, EGR control, or the like.
2. Statement of the Prior Art
Many of the patents of the prior art recognize the need for employing the enhanced accuracy of digital control systems for more accurately controlling one or more functions of an internal combustion engine.
U.S. Pat. No. 3,969,614 which issued to David F. Moyer, et al on July 13, 1976 is typical of such systems as are U.S. Pat. No. 3,835,819 which issued to Robert L. Anderson, Jr. on Sept. 17, 1974; U.S. Pat. No. 3,904,856 which issued to Louis Monptit on Sept. 9, 1975; and U.S. Pat. No. 3,906,207 which issued to Jean-Pierre Rivere, et al on Sept. 16, 1975. All of these patents represent a break-away from the purely analog control system of the past, but neither the accuracy, reliability, or number of functions controlled is sufficient to meet present day requirements.
Many of the modern electronic engine control systems simply stop operating in the event of a system failure particularly where the electronic operation thereof is dependant upon a digital clock or the like and the clock fails. No provisions are made for enabling the vehicle to travel at least a short distance for the purpose of repairs or the like.